Introduction

The other day we looked at the brand new Radeon HD 7990 6GB and found ourselves extremely impressed with what AMD was offering. Following that we looked at the overclocking side of things and found ourselves not quite as impressed. It's clear at the moment that there are some issues when it comes to overclocking, as we saw everything from big drops in performance to big gains and more often than not, no change at all.

One of the setups we really wanted to test is a pair of HD 7990 6GB cards in CrossFireX. Today, though, we'll be testing a setup that's actually quite an important one, especially in the case if you're already holding one of the pieces to the puzzle. With the release of the new HD 7990, we've got the ability to throw a new CrossFireX configuration into the mix. Being based on the HD 7970 GHz Edition core with just a small 50MHz drop in core speed, the similarities between the two cards are close - the most major difference being that the HD 7990 is a single PCB video card that has two GPUs on it.

While we'll of course be throwing a second card into the mix and essentially double the amount of cards we have in our system, the big thing to remember is that the maximum performance increase we'd expect to see is only around +50%, since we're adding just a third GPU into a two GPU mix that's created with the HD 7990 6GB.

Due to the fact that we've already looked at both cards in detail before, we'll simply just be moving from here onto the testbed. We'll take a quick look at the cards that will be in our graphs here today and check GPU-Z to make sure that everything looks fine.

Once we've gone through the motions we'll then get stuck straight into the performance and see just what this CrossFireX setup can bring to the party.